An optical navigation device is used to track the relative motion of a surface or object. Optical navigation is done by illuminating the surface or object and tracking its motion by analyzing the difference of two images recorded by an image sensor over a relatively short time frame. This concept can be witnessed, for example, in an optical computer mouse. As the mouse is moved across a tabletop or other surface, the relative motion is tracked and a navigation signal is generated.
FIG. 1 depicts a conventional optical navigation system 10. In particular, the optical navigation system 10 is a contact optical navigation system. The navigation system 10 includes a light source 12, a lens 14, and a sensor package 16. The light source 12, which generates light, is oriented at an angle with respect to a navigation surface 18. The light that is emitted by the light source 12 is directed through the lens 14 to the navigation surface 18. The navigation surface 16 reflects the light back through the lens 14 and into the sensor package 16. The angular configuration of the optical navigation system 10 to achieve reflection of the light on the navigation surface 16 consumes space and restricts the ability to incorporate the system in various spatially-constrained applications. This configuration of the conventional optical navigation system 10 also confines the optical navigation system 10 to contact navigation applications in close proximity to the navigation surface 18.